Description

Summary of the bug:
I'm seeing random green blocks coding mismatch when I decode a field coded H264 stream with ffmpeg or when I play it with ffplay (same problem with VLC). Please find the sample stream “h264_field_coding_green_block_artifacts.264” under upload.ffmpeg.org ftp server to reproduce the problem.
Also, I have noticed if I decode the stream many times with ffmpeg, the problem doesn't occur on the same frame, and it's random. So, you might need to decoded the attached stream 2 or 3 times to see the problem.
I have confirmed that the uploaded sample stream is decoded properly with latest JM reference decoder (JM 19.0), Windows Media Player and VanguardVideo? VCT v1.6, also I have analyzed it with many stream analyzer tools like Elecard StreamEye? v4.3 and Sencore CMA v5.0 and all of them didn't report any syntax error and they are able to decode the stream properly.
I did couple of tests to narrow down the problem and I have found that avcodec library has problem decoding h264 field coding streams with temporal direct mode.

The responsible functions are ff_h264_biweight_16_ssse3 and ff_h264_biweight_8_ssse3.
Only reproducible with -cpuflags mmx+ssse3 (which is equivalent to -cpuflags ssse3).
Afaict:
Only reproducible on (some?) Windows 64 systems.
Only reproducible with a high thread count (>4?).

I have tried the latest ffmpeg windows build version: 11777eb (2016-09-19), and I'm still seeing the same problem. Please, is there any update on this ticket? and is it possible to update its priority from normal to important since there are many customers using VLC player and complaining about those green block artifacts?

Thank you so much Hendrik for looking into this problem and fixing the issue, I have tried the new code and it's fine.
Also, thank you Carl and Michael for your help and support, it's much appreciated.